The present invention relates to thermoplastic resins containing additives that have been surface coated with a modifying agent. The surface coating permits improved compatibility between the additive and thermoplastic resin.
In Japanese Kokai 1-135868, published May 29, 1989, there are disclosed certain resin compositions containing (a) inorganic fillers and (b) polyphenylene ether type resins including maleic anhydride modified poly(2,6-dimethyl-1,4-phenylene)ether. The resins are useful for electrical parts.
According to the present invention there is provided a composition of matter comprising A) from 25 to 99 parts by weight of a thermoplastic resin and B) from 75 to 1 parts by weight of a glass, ceramic, polymeric or carbon reinforcing agent having a surface coating of a polar group functionalized polyarylene ether.
Polar group functionalized polyarylene ethers are a known class of compounds prepared by contacting polar group containing reactants with polyarylene ethers. The reaction is normally conducted at an elevated temperature preferably in a melt of the polyarylene ether under conditions to obtain homogeneous incorporation of the functionalizing reagent. Suitable temperatures are from 150.degree. C. to 300.degree. C. Polyarylene ethers are a known class of polymers having been previously described in U.S. Pat. Nos. 3,306,874, 3,306,875, 3,257,357, 3,257,358, and elsewhere. A preferred polyarylene ether is poly(2,6-dimethyl-1,4-phenylene)ether. The polyphenylene ethers are normally prepared by an oxidative coupling reaction of the corresponding bisphenol compound.
Suitable polar groups include the acid anhydrides, acid halides, acid amides, sulfones, oxazolines, epoxies, isocyanates, and amino groups. Preferred polar group containing reactants are compounds having up to 20 carbons containing reactive unsaturation, such as ethylenic or aliphatic ring unsaturation, along with the desired polar group functionality. Particularly preferred polar group containing reactants are dicarboxylic acid anhydrides, most preferably maleic anhydride. Typically the amount of polar group functionalizing reagent employed is from 0.01 percent to 20 percent, preferably from 0.5 to 15 percent, most preferably from 1 to 10 percent by weight based on the weight of polyarylene ether. The reaction may be conducted in the presence of a free radical generator such as an organic peroxide or hydroperoxide agent if desired. Preparation of polar group functionalized polyarylene ethers have been previously described in U.S. Pat. Nos. 3,375,228, 4,771,096 and 4,654,405 the teachings of which are herein incorporated in their entirety by reference thereto.
The general procedure for obtaining polar group functionalized polyarylene ethers is to contact a reagent containing both ethylenic unsaturation and the desired polar group previously specified. Generally if less than 0.01 weight percent of the polar group containing reactant is employed, less than desired compatibility between the reinforcing agent and the thermoplastic resin is attained.
The glass, ceramic, polymeric or carbon reinforcing agent may be in the shape of fibers having a length to diameter ratio (L/D) of greater than 5 or in the shape of particulates having (L/D) less than 5. Preferred particle diameters are from 0.1 micrometers to 1 millimeter. Suitable reinforcing agents include glass microspheres, glass fibers, ceramic whiskers, carbon fiber strands, boron nitride fibers, aramide fibers, etc. Preferred are glass fibers, glass roving or chopped glass fibers having lengths from 0.1 to 10 millimeters and L/D from 5 to 100. One such suitable glass fiber is available from Owens Corning Fiberglass under the designation OCF 414.TM..
The reinforcing agent may include a sizing agent or similar coating which among other functions, may promote adhesion between the reinforcing agent and the polar group functionalized polyarylene ethers. Suitable sizing agents may contain amine, aminosilane, and aminophosphine functional coupling agents. Preferred are aminosilane coupling agents such as 3-aminopropyltrimethoxysilane.
Thermoplastic resins suitably utilized in the present invention include homopolymers and copolymers of vinylaromatic monomers, particularly homopolymers and copolymers of styrene. Suitable comonomers include acrylnitrile, methyl methacrylate, N-phenylmaleimide, etc. Preferred are copolymers containing from 5 to 50 percent by weight of one or more such comonomers. Also included are rubber modified homopolymers and copolymers of vinylaromatic monomers such as high impact polystyrene-containing butadiene or styrene butadiene based elastomers; specifically high impact polystyrene and ABS resins. Additional vinylaromatic polymers are those having a stereoregular structure that is highly syndiotactic. Additional suitable thermoplastic resins include polycarbonates, polyamides, polyvinylchloride, polyesters, polyimides, and polyarylene ethers. In addition, mixtures of all of the foregoing thermoplastic resins may additionally be employed.
A most preferred thermoplastic resin is syndiotactic polystyrene prepared by coordination polymerization of styrene monomer under conditions to provide a high degree of syndiotacticity. Preferred are those polymers containing greater than 50 percent syndiotacticity at a racemic triad. Such polymers are known in the art having been previously disclosed in U.S. Pat. Nos. 4,680,353, 4,959,435, 4,950,724, 4,774,301, and elsewhere. The teachings of the foregoing U.S. patents are incorporated herein in their entirety by reference thereto.
The compositions of the present invention are prepared by combining the respective components under conditions to provide uniform dispersal of the reinforcing agent. The surface coating is suitably applied to the reinforcing agent by contacting the same with a solution of the polar group functionalized polyarylene ether. Suitable solvents for dissolving the polar group functionalized polyarylene ether include methylene chloride, trichloromethane, trichloroethylene, trichloroethane, etc. Preferably the concentration of polar group functionalized polyarylene ether in the solution is from 0.1 weight percent to 20 weight percent, preferably 0.5 to 2 percent by weight. After coating of the reinforcing agent the solution is removed such as by evaporation, devolatilization, vacuum drying, etc.
The resulting surface coating is desirably from 0.001 to 10 weight percent of the uncoated reinforcing agent weight. Homogeneous incorporation of the thermoplastic resin and coated reinforcing agent is obtained by mechanical mixing devices such as extruders, ribbon blenders, solution blending or any other suitable technique. Preferred compositions are those containing from 5 to 95 parts thermoplastic resin and 49 to 5 parts reinforcing agent.
Additional additives such as fillers, elastomers, blowing agents, extrusion aids, antioxidants, pigments, plasticizers, stabilizers, lubricants, etc. may also be included in the composition in amounts up to 50 percent, preferably up to 25 percent by weight.
Having described the invention the following example is provided as further illustrative and is not to be construed as limiting. Unless states to the contrary parts and percentages are based on weight.